[llvm-bugs] [Bug 46585] New: [DAGCombiner] ZERO_EXTEND_VECTOR_INREG/SIGN_EXTEND_VECTOR_INREG of undef incorrectly folded to undef

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=46585

            Bug ID: 46585
           Summary: [DAGCombiner]
                    ZERO_EXTEND_VECTOR_INREG/SIGN_EXTEND_VECTOR_INREG of
                    undef incorrectly folded to undef
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Common Code Generator Code
          Assignee: unassignedbugs at nondot.org
          Reporter: craig.topper at gmail.com
                CC: llvm-bugs at lists.llvm.org

Even if the input is undef, ZERO_EXTEND_VECTOR_INREG should still produce 0s in
the extended bits. SIGN_EXTEND_VECTOR_INREG should produce sign bits that are
the same. Therefore we can't fold these to undef.

Reduced from ispc issue https://github.com/ispc/ispc/issues/1793

-- 
You are receiving this mail because:
You are on the CC list for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-bugs/attachments/20200704/6c7e8039/attachment.html>